Performance Comparison of Overlay and Peer Models in IP/MPLS over Optical Networks

We study the connection establishment of label switched paths (LSPs), and compare the LSP blocking performance of the overlay and peer models in IP/MPLS over optical networks. We consider two dynamic routing algorithms for the establishment of LSP connections, of which one is for the overlay model and the other is for the peer model. Our investigations on two typical network topologies, namely NSFNET and ARPA2 networks, show that the number of add/drop ports (or transceivers) on optical cross-connects (OXCs) has a significant impact on the LSP blocking performance for both models. We show by computer simulation that in each case, there is a threshold value for the add/drop ratio, which can achieve almost the best blocking performance. This threshold value remains virtually unchanged as the traffic load varies, but it does depend on the network topology and the number of wavelengths per fiber. This will then indicate the number of add/drop ports to be used so that one can achieve a near optimal blocking performance without incurring unnecessarily excessive network costs. Our investigations reveal that the peer model achieves a much better blocking performance than the overlay model when the number of add/drop ports is relatively high, but that this is not always true when the number of add/drop ports is small.     

用MPLS技术实现IP over WDM

提出了一种全新的高速宽带组网技术－基于MPLS的IPoverWDM网络技术,并对其进行了深入研究。这个方案在光联网技术中综合了目前先进的MPLS流量工程控制技术,特别适合于由可重构的OADM和OXC组成的以数据业务为核心的互联网络系统,而且它为最终在IP路由器上直接提供WDM复用功能铺平了道路。     

Architecture and Engineering Issues in Building an IP over WDM Networks

The technologies of IP over WDM have presently received increasing attention owing to the rapid growth in Internet traffic and the need for next-generation Internet technologies. The challenge now is how to integrate the services of IP over WDM optical networks to take full advantages of WDM technologies and IP technologies, and yield a high-throughput optical platform directly underpinning next generation data networks. This article discusses some of the architecture and technology issues for the design of IP over WDM optical networks.     

IP/MPLS over WDM网中考虑链路 负载平衡的保护设计

利用网络链路资源被占用的部分信息实现保护资源共享,可以极大地改善网络对业务的丢弃性能.这对采用多协议标记交换(MPLS,Multiprotocol Label Switching)技术的IP over WDM网络来说,并不需要太大的代价.基于此,本文提出了在IP over WDM网中考虑通路保护的动态路由算法.对工作通路的选取,算法对选路成本和路由长度作了折衷考虑;而对于保护通路,则对其共享能力和路由长度作了权衡.仿真结果表明,本文算法不管是对业务的丢弃性能,还是对网络的链路负载平衡度,均取得了较满意的结果.     

Optimum Arrangement of Reliable Label-Switched Paths in MPLS Over Optical Networks

In MPLS (Multi-Protocol Label Switching) over optical networks, both the optical level and the MPLS level fault recovery can be considered. Generally, a more flexible path arrangement can be realized by the MPLS level recovery, while fast recovery can be achieved by the optical level recovery. When the optical level recovery is adopted, only normal traffic is carried through the working lightpaths and only recovered traffic is carried through the backup lightpaths. In contrast, the working LSPs (Label-Switched Paths) and the backup LSPs corresponding to other working LSPs can be accommodated into an identical lightpath when the MPLS level recovery is adopted. By such sophisticated accommodation of LSPs into the lightpaths, lightpath bandwidth can be utilized efficiently under the condition that the bandwidth utilization is restricted to attain the given objective of transfer quality for the MPLS packets in the normal state and unrestricted in a short time a failure occurs somewhere in the network. This paper proposes a simple mathematical programming model to obtain the optimum arrangement of the working and backup LSPs assuming the MPLS level recovery and a practical LSPs provisioning mode. By comparing the minimized network cost obtained from the optimum arrangement of the working and backup LSPs with the network cost resulting from the optical level recovery, this paper quantitatively evaluates the effectiveness of such bandwidth utilization improvement obtained from the MPLS level recovery and reveals that the MPLS level recovery can actually reduce the network cost due to its flexible arrangement of LSPs on the lightpaths.     

IP的出路--多协议标签交换(MPLS)

作为下一代网络的来越重要的角色.介绍了MPLS的概念、组成,详细分析了其工作原理及其承载的各种应用,为打造支持未来3G业务的精品IP承载网提供了一些参考.     

IP over DWDM光互联网技术

文中对基于 IP over WDM的新型数据网络体系结构——光互联网络技术进行了探讨。在分析三种构造未来信息网络解决方案的基础上 ,着重对基于 IP over WDM的光互联网络的关键技术和未来发展方向进行了研究。     

MPLS与IP组网模式的演变(续)

本文首先简要回顾了ＩＰ与ＡＴＭ结合技术的演变。在此基础上,指出ＭＰＬＳ是对ＩＰ现有组网模式的革新,包括路由和转发体系结构。与基于传统路由器加专线的ＩＰ组网模式相比。基于ＭＰＬＳ的ＩＰ新组网模式在支持业务质量（ＱｏＳ）、流量工程规划、虚拟专用网（ＶＰＮ）等方面具优势。最后探讨了下一代公用网络核心平台的可能结构,并指出ＭＰＬＳ＋ＤｉｆｆＳｅｖ是未来的发展方向。     

WDM智能光网络与IP业务

详细分析了 ＷＤＭ光网络的结构以及联网技术的演进过程，对如何压扁网络层次，实现ＩＰ直接ｏｖｅｒ ＷＤＭ，发挥 ＷＤＭ光传送网的巨大带宽优势进行了研究，提出 ＭＰＬＳ是当前解决 ＩＰ层与光层的融合以及跨层管理问题的关键技术。     

IP承载网技术讲座第1讲 IP/MPLS骨干网设计

本文首先从建设模式,网络结构和业务承载等角度分析了IP/MPLS骨干网的模型,然后就IP/MPLS骨干网设计中采用的关键技术进行了探讨并给出了解决思路,最后简要介绍了中兴通讯的IP/MPLS骨干网解决方案的特点和方向.     

IP/MPLS-Over-WDM网络的生存性

Internet的发展和数据业务的爆炸性增长对当前网络提出了更高的要求。网络将演变为IP/MPLS-over-WDM。对于这种以光网络为基础的网络构架,网络生存性问题变得尤为重要。由于以数据业务为中心的光网络至少包含IP层和光层,笔者提出了几个在多层网络生存性面临的问题,并给出了几种方案。最后,讨论了IP/MPLS--Over-WDM特有的生存性思考。     

Providing differentiated services for multi-class traffic in IP/MPLS over WDM networks

Providing differentiated services in IP/MPLS over WDM networks has attracted a lot of recent attention. This article extends the Path Inflation Control (PIC) policy recently proposed by us to provide differentiated services in IP/MPLS over WDM networks with traffic grooming. Three different algorithms are considered for provisioning differentiated services. The simulation results show that, with two of the three algorithms, the network cannot only provide differentiated services when the traffic load is high but also gives significantly lower blocking for the lower priority class traffic and for the overall traffic at low traffic loads.

Historical data learning based dynamic LSP routing for overlay IP/MPLS over WDM networks

Overlay IP/MPLS over WDM network is a promising network architecture starting to gain wide deployments recently. A desirable feature of such a network is to achieve efficient routing with limited information exchanges between the IP/MPLS and the WDM layers. This paper studies dynamic label switched path (LSP) routing in the overlay IP/MPLS over WDM networks. To enhance network performance while maintaining its simplicity, we propose to learn from the historical data of lightpath setup costs maintained by the IP-layer integrated service provider (ISP) when making routing decisions. Using a novel historical data learning scheme for logical link cost estimation, we develop a new dynamic LSP routing method named Existing Link First (ELF) algorithm. Simulation results show that the proposed algorithm significantly outperforms the existing ones under different traffic loads, with either limited or unlimited numbers of optical ports. Effects of the number of candidate routes, add/drop ratio and the amount of historical data are also evaluated.     

Architectures and Performance of Optical Packet Switching over WDM

Packet switching over wavelength division multiplexing (WDM) channels is considered with the aim to investigate algorithms for wavelength assignment and to define feasible switch architectures, in the presence of connectionless or connection-oriented transfer modes. In particular, as regards the connection-oriented scenario, mapping of virtual connections onto wavelengths operated by network nodes is considered and procedures are proposed to achieve statistical multiplexing efficiency by dynamic wavelength re-assignment. Switch architectures to support dynamic wavelength encoding and the related performance evaluation are presented and discussed in the paper, evidencing the benefits of packet switching over WDM.     

光互联网与IP over DWDM技术的演进

探讨了光互联网的支撑技术和演进策略,分析了IP over DWDM等关键支撑技术的难点与发展趋势。首先,比较分析了若干种典型的网络层次模型及其性能,指出IP over DWDM是实现未来宽带互联网的关键支撑技术;其次,分析了IP over DWDM的技术难点,指出全光信号处理和多协议标签交换技术是实现IP over DWDM的重要手段,并预言了在相关技术成熟后,光分组网技术将进一步推动光互联网的发展。     

An efficient mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks

This paper proposes an efficient overlay multicast provisioning (OMP) mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks. To facilitate request provisioning, OMP jointly utilizes a data learning (DL) scheme on the IP/MPLS layer for logical link cost estimation, and a lightpath fragmentation (LPF) based method on the WDM layer for improving resource sharing in grooming process. Extensive simulations are carried out to evaluate the performance of OMP mechanism under different traffic loads, with either limited or unlimited port resources. Simulation results demonstrate that OMP significantly outperforms the existing methods. To evaluate the respective influences of the DL scheme and the LPF method on OMP performance, provisioning mechanisms only utilizing either the IP/MPLS layer DL scheme or the WDM layer LPF method are also devised. Comparison results show that both DL and LPF methods help improve OMP blocking performance, and contribution from the DL scheme is more significant when the fixed routing and first-fit wavelength assignment (RWA) strategy is adopted on the WDM layer. Effects of a few other factors, including definition of connection cost to be reported by the WDM layer to the IP/MPLS layer and WDM-layer routing method, on OMP performance are also evaluated.     

MPLS在未来IP网络中的应用设想

分析了MPLS在未来IP网络中的可能的应用前景,认为信息骨干网络可能由光的MPLS和电的MPLS两层网络组成,并完成骨干网上的IP路由,边缘路由器完成边缘的IP路由交换,着重提出了光的MPLS的实现方法和基本原理及结构。     

多协议标签交换(MPLS)网络核心技术讨论

对MPLS（multiprotocol label switching,多协议标签交换）的两种核心协议RSVP、CR－LDP以及两种IP QoS体系结构（int-serv、diff-serv）进行了比较和讨论。     

光开关在自动交换光网络中的研究与检测技术

作为自动交换光网络中的核心器件,光开关将在未来全光网中发挥着重要作用,并成为未来光联网的关键技术。本文总结光开关实现方法的最新进展,重点介绍电光效应开关和超高速光控开关的工作原理和实际应用。最后阐述我实验室在光开关性能检测方面所做的研究工作.     

全光网络中光通道连接的分布式管理

全光通信网络中 ,光通信连接是透明的 ,可以承载不同格式和速率的信号。文中着重研究全光网络中光通道连接的控制机制 ,提出了波长路由光网络的分布式控制方案 ,从而实现光通道连接的可靠建立和拆除。